1. Field of the Invention
This invention is in the field of continuous enameling furnaces wherein the ware is continuously passed through succeeding drying, pre-heating, heating and cooling zones while hot combustion gases which serve to fuse the pre-applied coating to the surface of the ware give up essentially all of the usable heat in passing from the hot heating zone into the cooler pre-heating zone, and ultimately into a drying zone for removing moisture from the incoming ware before the combustion gases are exhausted.
2. Description of the Prior Art
There have been some designs of continuous enameling furnaces using radiant tubes of straight and U tube configurations. The exhaust in such furnace assemblies generally went out straight through the stack into a collector hood. The very high temperature of the gases made it difficult to dispose of or salvage the heat from the combustion gases properly and this added considerably to the cost.
There are also continuous enameling furnaces of the muffle furnace type using a refractory lining which is heated from behind by means of burners. This type of assembly exhausted the combustion gases under the floor of the furnace to a flue which extended through the roof. Since the exhaust gases were frequently at a temperature as high as 1800.degree. F., the problem of waste gas disposal was acute. Some attempts were made to use heat exchangers in the stack but, to my knowledge, these were not successful.